Watercraft

ABSTRACT

The invention relates to a tugboat.  
     Such a tugboat is provided with the following features: with a drive which is disposed in the region of the bow of the tugboat,  
     According to the invention such a tugboat is provided with the following features:  
     A roller is provided in the region of the stern of the tugboat which is substantially arranged perpendicularly and is held rotatably about its longitudinal axis;  
     The roller is associated with a drive.

[0001] The invention relates to a watercraft with a drive located in the bow region of the watercraft. It especially concerns watercraft with controllable drives. Such watercraft are also known as tugboats. The controllable drives can either be so-called rudder propellers or cycloidal propellers of the type of a so-called Voith-Schneider® propeller.

[0002] Such ships usually have a central fin. It is located on the bulge in its longitudinal central plane, namely in the region relating to the longitudinal axis of the ship which is disposed at the other end than the drive

[0003] Such ships are used as tugs or towing boats for maneuvering and escorting large freight ships, and tankers in particular. These ships are often called escort tugboats in fulfilling this task. During the escorting process the freight ship is in drive and the escorting tugboat is connected at the stem of the boat with the freight ship by way of a cable. It the rudder system and/or the main drive system fails in the freight ship, the escorting tugboat must produce large transverse forces in order to keep the large freight ship on the desired course. That is why it is necessary to produce the highest possible transverse force with the entire hull on the escorting tugboat.

[0004] In fulfilling the escorting task, the escorting tugboat is used with a fin in such a way that the driving direction of the ship is such that the fin faces forwardly. This driving direction is precisely opposite to the driving direction in other towing operations where the fin faces backwardly.

[0005] The current state of high-performance rudder technology comprises transverse jet devices, propulsive thrust systems and special rudders with which maneuvering is already highly efficient. The requirements have increased over time, however, so that further improvements are desirable.

[0006] The invention is therefore based on the object of providing a watercraft, and an escorting tugboat in particular, in such a way that the highest possible transverse forces are produced during the drive and that freight ships can be held securely on course. The object is to be achieved with a more minimal constructional effort as has been achieved with previously known means.

[0007] This object is achieved by the characterizing features of claim 1.

[0008] The inventors have made use of an element which, although already known, is the rotatably held roller (cf. “Schiff & Hafen” [Ship & Harbor], No. 4/1980). Such a rotatable roller is arranged on the rudder there, i.e. astern. According to the invention, however, such a rotating roller is arranged remote from the drive, i.e. in the region of the other end of the water craft, which differs from the location where the drive is situated. The idea is surprising in the respect that it must seem peculiar for the ship construction engineer. According to the invention, the rotatable roller is arranged in the region of the fin and there preferably at the end of the fin which is remote from the drive. The rotatable roller is best arranged in the longitudinal central plane or at least parallel thereto. Its longitudinal axis extends either in the vertical direction or inclined against the vertical under a certain angle, e.g. 10, 20 or 30 degrees.

[0009] It is particularly appropriate to constructionally integrate the rotatable roller in such a way that the rotatable roller forms the edge of the fin which is flowed against. The fin assumes the bearing in this case.

[0010] The arrangement can be made in such a way that the rotatably held roller can be swiveled out of the longitudinal central plane about a vertical axis or about an axis which is slightly inclined with respect to the vertical.

[0011] The rotatably held roller is provided with a drive. The roller can thus be made to rotate with a circumferential speed which amounts to a multiple of the ship's speed. The roller can be provided with a profiled surface, e.g. with elevations or recesses. The drive output is minimal. It is generally less than 50 kW.

[0012] The effect of the invention is surprising. It is possible to achieve considerable lifting forces with the rotatable roller, i.e. forces which extend perpendicularly to the flow and are disposed in the plane of the water surface. Tests have shown that the invention increases the lateral force of the watercraft by approx. 20%.

[0013] A control device is preferably associated with the rotatable roller. It is used to control the direction of rotation or the rotational speed of the roller or both the values.

[0014] Control can be effected in two ways: On the one hand, the control device can act depending on the transverse thrusting direction of the main driving system and/or optionally provided rudders, or on the other hand depending on the cable system, meaning in the direction of the cables. This can be understood as follows: The cable is generally guided between two posts which bear rolls for guiding the cable. The force can be detected in this process which is exerted by the cable on either the one or the other post. The control device can then control the rotational direction or the rotational speed of the roller, or both parameters, depending on the aforementioned control values.

[0015] With a minimum of constructional effort it is thus possible to substantially improve the lateral force of a watercraft as compared with previously known vehicles, This leads to the following advantages for the escorting task:

[0016] the turning capabilities of the freight ship during maneuvering is minimized;

[0017] the time until the performance of the turning maneuver is strongly reduced,

[0018] the parallel displacement can be performed easily and quickly;

[0019] the slow drive can be performed with ease even under difficult current conditions;

[0020] shearing maneuvers can be initiated or completed without any major advance forces.

[0021] Numerous modifications of the invention are possible, The roller need not necessarily be circular-cylindrical. It can be provided with the shape of a cylinder with the cross section of a polygon. In addition, it needn't be cylindrical at all. Instead, it may be provided with a cross section which differs at different places of the length. As a result, it can be provided in the zone of the bulge with a circular cross section with a relatively large diameter and at the other end, averted from the bulge, with a circular cross section of a relatively small diameter.

[0022] The invention will be generally employed in tugboats with two drives, of which one each is disposed on one side each of the longitudinal central plane. It is also possible to use the invention in a tugboat with only a single drive. It is also possible to provide two fins instead of one fin which are arranged parallel next to one another, with one each being on either side of the longitudinal central plane.

[0023] The invention is now explained in closer detail by reference to the enclosed drawing, which shows the following in detail:

[0024]FIG. 1 shows an escorting tugboat with controllable drives.

[0025] The escorting tugboat as shown in FIG. 1 is provided with controllable drives 1. They are located on either side of the longitudinal central plane of the tugboat, namely in the region of its one end.

[0026] At the opposite end there is located a fin 2. The fin 2 is provided with a roller 3 in accordance with the invention.. It is provided with a roller drive (not shown) in order to rotate the roller about its own longitudinal axis.

[0027] In the present case the two tugboat drivers are Voith-Schneider® propellers. Other types of drives can be considered instead. 

1. A tugboat; with a drive (1) which is disposed in the region of the bow of the tugboat; with a roller (3) being provided in the region of the stem of the tugboat, which roller is substantially arranged perpendicularly and is held rotatably about its longitudinal axis; with a roller drive being associated with the roller (3); with one or several fins (2) being provided in the region of the central longitudinal plane or outside of the tugboat; with the roller (3) being disposed in the off-flow region of the fin (2).
 2. A tugboat according to claim 1 , wherein the roller (3) is inclined against the perpendicular.
 3. A tugboat according to claim 1 or 2 , wherein the roller (3) is joined with the fin (2) or carried by the same,
 4. A tugboat according to one of the claims 1 to 3 , wherein the roller (3) can be swiveled out of the longitudinal central plane.
 5. A tugboat according to claim 4 , wherein the roller (3) can be swiveled out with its upper end by a different amount from the longitudinal central plane than with its lower end.
 6. A tugboat according to one of the claims 1 to 5 , wherein the jacket surface of the roller (3) is profiled.
 7. A tugboat according to one of the claims 1 to 6 , wherein the drive comprises a propulsion member which is controllable by 360°.
 8. A tugboat according to claim 7 , wherein a propulsion member controllable by 360° is each provided on either side of the longitudinal central plane of the tugboat.
 9. A tugboat according to one of the claims 1 to 8 , wherein a control device is provided for controlling the direction of rotation and/or the rotational speed of the roller (3) depending on the direction of control of the drive.
 10. A tugboat according to one of the claims 1 to 9 , wherein a control device is provided for controlling the direction of rotation and/or the rotational speed of the roller (3) depending on the direction of the cable or the force exerted by the cable onto a stop. 